igneous
Diorite (Dalmatian Stone)
Phaneritic Plutonic Diorite
Hardness: 6-7 on Mohs scale; Color: Mottled black and white/gray; Luster: Dull to sub-vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0
- Hardness
- 6-7 on Mohs scale
- Color
- Mottled black and white/gray
- Luster
- Dull to sub-vitreous
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Mottled black and white/gray; Luster: Dull to sub-vitreous; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.8-3.0
Formation & geological history
Formed through the slow cooling of intermediate composition magma beneath the Earth's surface (intrusive). The dark spots are typically hornblende or biotite, while the white is plagioclase feldspar.
Uses & applications
Used in construction as crushed stone, for floor tiles, countertop material, and occasionally as a gemstone in tumbled form or cabochons.
Geological facts
Commonly referred to as 'Dalmatian Jasper' in the jewelry trade, though it is geologically an igneous rock (diorite) and not a true jasper (sedimentary chalcedony).
Field identification & locations
Identified by its 'salt and pepper' appearance with distinct interlocking crystals. Frequently found in batholiths and mountain-building zones. Collectors should look for the characteristic granular texture.
